Along with an increase in the degree of integration of a semiconductor device, a semiconductor integrated circuit has been further micropatterned.
For example, considering a semiconductor exposure apparatus which transfers a circuit pattern onto a silicon substrate, the wavelength of exposure light used in exposure must be shortened for micropatterning. The wavelength has been shortened from a g-line and an i-line to a KrF laser beam, an ArF laser beam, an F2 laser beam, a soft X-ray radiated from an SR ring, or the like.
The exposure light with a short wavelength, such as the F2 laser beam or soft X-ray is greatly attenuated in air. Thus, the exposure unit of an exposure apparatus is stored in a chamber, wherein an N2 atmosphere or a pressure-reduced He atmosphere providing small attenuation of the exposure light is formed, or a vacuum atmosphere is formed for an electron beam exposure apparatus, and the like. In a substrate processing apparatus, or the like, when process gas is different from the air or when oxidation of a resist on the substrate is to be prevented, an atmosphere different from the air or the vacuum atmosphere is formed in a chamber.
Conventionally, as such a processing apparatus, an arrangement shown in FIGS. 7 and 8 is known. The substrate processing apparatus of this type includes a process chamber 1 serving as the first chamber which stores a process station for, e.g., exposing the substrate in an atmosphere different from the air, and a substrate supply portion 10 arranged in the air.
The substrate supply portion 10 includes a substrate carrier support portion 101, on which a carrier 102 storing the substrate is placed manually or by an automatic transfer apparatus.
In order to transfer a substrate to be processed between the process chamber 1 and the substrate supply portion 10, a load-lock chamber 3 serving as a second process chamber is arranged. A plurality of load-lock chambers 3 may be arranged for loading/unloading.
In the apparatus shown in FIGS. 7 and 8, the pressure-reduced He atmosphere is formed in the process chamber 1, which stores the processing unit.
The load-lock chamber 3 has a first gate valve 4 on the air side to shield the load-lock chamber 3 from the substrate supply portion 10 in the air, and a second gate valve 5 on the process chamber 1 side to shield the load-lock chamber 3 from the process chamber 1. The load-lock chamber 3 also has an exhaust mechanism 12 for exhausting gas from the load-lock chamber 3, an He gas supply portion 13 for supplying He gas into the load-lock chamber 3, and an N2 gas supply portion 14 for supplying N2 gas into the load-lock chamber 3.
The load-lock chamber 3 includes a substrate holding chuck 6 designed to store, e.g., one or a plurality of substrates.
In the air, a first transfer mechanism 7 for transferring the substrate between the substrate carrier 102 on the carrier support portion 101 and the load-lock chamber 3 is arranged. In a preliminary chamber 2, connected between the process chamber 1 and the load-lock chamber 3, a second transfer mechanism 8 for transferring the substrate between the load-lock chamber 3 and a process station (exposure process portion) 20 is arranged.
The operation of the above conventional apparatus will be described below.
The first transfer mechanism 7 extracts one substrate from the substrate carrier 102 placed on the carrier support portion 101, and transfers the substrate to the load-lock chamber 3.
When the substrate is loaded into the load-lock chamber 3 and placed on the substrate holding chuck 6, the first gate valve is closed to shield the load-lock chamber 3 from the air. The atmosphere in the load-lock chamber 3 is purged.
Purging the atmosphere in the load-lock chamber 3 is performed to be described below.
A vacuum exhaust valve 122 is opened in a state wherein the load-lock chamber 3 is shielded from the air and the chamber 1 by closing the first and second gate valves 4 and 5. The gas is then exhausted from the load-lock chamber 3 by a vacuum exhaust pump (not shown) via a vacuum exhaust pipe 121.
The chamber 3 is evacuated to a predetermined vacuum degree. After evacuating the chamber 3 to the predetermined vacuum degree, the vacuum exhaust valve 122 is closed, and the evacuation is stopped.
The gas supply valve is then opened. The load-lock chamber 3 shown in FIG. 8 includes an He gas supply valve 132 and an N2 gas supply valve 142. At this stage, the He gas supply valve 132 of these supply valves is opened to supply the same gas as the atmosphere in the chamber 1 storing the process station (exposure process portion) 20.
Until the pressure in the load-lock chamber 3 equals that in the process chamber 1, the He gas is supplied. When the pressure in the load-lock chamber 3 equals that in the process chamber 1, the He gas supply valve 132 is closed to stop supplying the He gas.
When supply of the He gas is stopped, the second gate valve 5 is opened. The substrate on the substrate holding chuck 6 is extracted by the second transfer mechanism 8 in the preliminary chamber 2, and transferred to the process station (exposure process portion) 20 in the process chamber 1.
The substrate processed in the process station (exposure process portion) 20 is returned to the substrate carrier 102 via the load-lock chamber 3 by the first and second transfer mechanisms 7 and 8.
During evacuation of the load-lock chamber 3 in the above-apparatus, adiabatic expansion occurs in the load-lock chamber 3, and the gas in the load-lock chamber 3 is cooled.
At this time, since the substrate and the substrate holding chuck 6 in the load-lock chamber 3 are exposed to the gas in the load-lock chamber 3, their temperatures are reduced along with cooling the gas. The substrate cooling by the adiabatic expansion in the load-lock chamber 3 is loaded into the process chamber 1 and processed at the end of purging the atmosphere.
In the exposure apparatus, the substrate temperature needs to be controlled with high precision in order to obtain high transfer precision, the high line-width precision, and the like. However, in the conventional apparatus, the temperature of the substrate loaded into the process chamber 1 via the load-lock chamber 3 is reduced, as described above. Hence, the transfer precision deteriorates when exposure is performed for the wafer in this state, thus posing a problem.
As a prior art arrangement related to the problem as described above, an example is available, in which, in order to control the substrate to a predetermined temperature, the substrate is brought into contact with ambient gas and a substrate transfer means to gradually increase the substrate temperature to the predetermined temperature.
Such a method requires a long period of time for the substrate to reach the predetermined temperature. This makes it difficult to improve the throughput. Specifically, in the apparatus in which the chamber is evacuated, since heat exchange is not performed with the ambient gas, thermoregulation by the ambient gas is not expected.
Hence, in this case, the substrate is thermally regulated only by contact with the substrate transfer means. This requires a longer period of time for the substrate to reach the predetermined temperature.